Geographic Routing without Location Information Ananth Rao, Sylvia Ratnasamy, Christos...
-
Upload
emery-phillips -
Category
Documents
-
view
215 -
download
0
Transcript of Geographic Routing without Location Information Ananth Rao, Sylvia Ratnasamy, Christos...
Geographic Routing without Location
Information
Geographic Routing without Location
InformationAnanth Rao, Sylvia Ratnasamy,
Christos Papadimitriou, Scott Shenker and Ion Stoica
MobiCom 2003
Outline• Introduction• Coordinate Construction
– Perimeter Nodes Know Location– Perimeter Nodes are Known– No Location Information
• Routing Algorithm• Performance• Conclusion
INTRODUCTION• Geographic Routing protocol
– Refer to nodes by their location• Not address
– To route greedily• Towards the destination
• However– Location information is not available at the
nodes• Geographic methods cannot be used
Introduction (cont.)• In this paper
– Define a scalable coordinate-based routing algorithm• Does not rely on location information• Can be used in a wide variety of ad hoc
and sensornet environments• virtual coordinates
– x_coordinates– y_coordinates
COORDINATE CONSTRUCTION
• A method for constructing virtual coordinates without location information
• Perimeter nodes– Perimeter nodes know their location– Perimeter nodes know that they are
perimeter nodes, but don’t know their location
– Nodes know neither their location, nor whether they are on perimeter
COORDINATE CONSTRUCTION
(cont.)
64 perimeter nodes8 units
Perimeter Nodes Know Location
• Relaxation procedure– All non-perimeter nodes can determine
their coordinates– X_coordinates
Y_coordinates
X1………………………..Xn
x3 x5x4
Perimeter Nodes Know Location
(cont.)
Initial coordinates(100,100)
3200 nodes
Perimeter Nodes Know Location
(cont.)
10 iterations
Perimeter Nodes Know Location
(cont.)
100 iterations
Perimeter Nodes Know Location
(cont.)
1000 iterations
Perimeter Nodes are Known
• Perimeter nodes know that they are perimeter nodes, but don’t know their location– perimeter nodes flood the network
• HELLO message• To discover the distances (in hops)
between all perimeter nodes• Triangulation algorithm
Perimeter Nodes are Known (cont.)
• Step 1– Each perimeter node broadcasts a HELLO message– perimeter vector
• Step 2– Each perimeter node broadcasts its perimeter vector– Every perimeter node knows the distances between
every pair of perimeter nodes
• Step 3– Every perimeter node uses a triangulation algorithm
to compute the coordinates
Perimeter Nodes are Known (cont.)
No Location Information
• Nodes know neither their location, nor whether they are on perimeter
• Perimeter node criterion– if a node is the farthest away, among
all its two-hop neighbors, then the node decides that it is on the perimeter
No Location Information (cont.)
Routing Algorithm• Packets are routed according to
three rules– Greedy– Stop– Dead-end
Performance• 200 × 200 square units• Radio range is 8 units
Performance (cont.)
Performance (cont.)
hops
Performance (cont.)
Conclusion• This paper present an algorithm
for assigning coordinates to nodes– virtual coordinates
• used to perform geographic routing